Ford 2003 Mustang Workshop Manual page 2590

1. NOTE: Use a backup wrench to hold the case fitting secure.
Install the fluid cooler tubes at the transmission.
2. Install the fluid cooler tube bracket at the engine.
3. Install the nuts.
4. Lower the vehicle.
5. Connect the battery cables.
6. Fill the transmission with fluid and verify proper operation.
Use Motorcraft MERCON® V Automatic Transmission Fluid XT-5-QM or equivalent
meeting MERCON® V specification.